FIGS. 1-3 illustrate a known T-handle latch. Such latches are used for latching and locking a variety of doors, for example the tailgate of a pick-up truck. The latch comprises a housing 10, a handle 12 rotationally mounted within the housing 10, and a latch actuating member 40 mounted on the end of the handle for rotation therewith. The housing 10 is primarily intended for reception in an opening of an item to be latched, such as a door, and is fixed, in use, against rotation within the opening at a selected angular position.
The handle 12 comprises a grip 14 made up of wings 16 and a cylindrical portion 18. Extending from the grip 14 is a stepped shaft 20, including a first stepped portion 22, a second stepped portion 24, and a third stepped portion 26.
The third stepped portion 26 extends outwardly from the left end of the housing 10 as seen in FIG. 1, where it is received within an end cap 30. The end cap 30 is fixed against rotation with respect to the stepped shaft, as by lands 31 on the third stepped portion 26. End cap 30 also is fixed on the end of the shaft 20, as by a washer 32 and a screw 34. Alternatively, the end cap 30 can be pinned in place or may be held by a clip or a swaged part of the shaft.
It will be seen that the end cap 30 and stepped shaft 20 rotate as a unit within housing 10. Accordingly, the end cap 30 and stepped shaft 20 will be referred-to collectively as a shank of the handle 12.
The shank of the handle is received in shank receiving opening 42 of the actuating member 40. As seen in FIG. 2, the opening 42 is formed in part by straight side walls 44 that cooperate with lands 46 of the end cap 30, thereby helping to insure that the actuating member 40 will rotate when the shank of the handle is rotated. Positioning nut 50 is received on threads 48 of end cap 30, thereby retaining the actuating member 40 on the shank of the handle.
Lands 52 are formed on opposite sides of housing 10, these lands being designed to cooperate with similarly-shaped portions of the opening of the item to be latched in which the housing is received.
One end of a return spring 70 is received in an opening 72 of the actuating member 40. The other end of the return spring 70 is received in opening 74, formed in the housing 10. Return spring 70 is a tension spring, and serves to bias the rotation of the actuating member 40 and handle 12 to return to a neutral home position following the turning of the handle 12 by a user. Torsional coil springs have also been used.
For purposes of mounting the latch, a mounting nut 60 is received on threads 62 of the housing 10. In use, the item to be latched is held between rear face 54 of a flange 56 and front face 58 of mounting nut 60. It is generally difficult or impossible to mount the latch with positioning nut 50, latch actuating member 40 and mounting nut 60 mounted in place. For this reason, return spring 70 must often be disconnected from actuating member 40. If the opening in the item to be latched is sufficiently large, return spring 70 may be left connected to housing 10 during the insertion of the housing 10 into the opening. If not, return spring 70 must be disconnected from the housing 10.
The combination of housing 10 and attached handle 12 is then inserted into the opening, whereupon the mounting nut 60 is threaded onto the housing 10 until the housing is tightly secured to the item to be latched. Actuating member 40, return spring 70 and position nut 50 are then attached. In the past mounting clips have on occasion been used in place of the nut 60.
Various embodiments of actuating members are known. In the embodiment shown in FIGS. 1-3, actuating member 40 is provided with two working openings 76. Such openings are intended for the pivotal attachment of actuating rods or similar elements of latch hardware. In order to facilitate the attachment of such hardware, the actuating member 40 is designed so that it may be adjusted transversely with respect to the shank of the handle 12. For this purpose, as may be seen in FIG. 2, the shank receiving opening 42 has a length in a transverse direction (shown top to bottom in FIG. 2) that is greater than the width of the received portion of the shank as measured in the same direction. Thus, the actuating member 40 may slide transversely of the shaft during installation. Upon achieving a desired position, the position nut 50 may then be tightened, thereby adjusting the latch to the actuating rods or other latch hardware. The end cap is symmetrical to allow the actuating member 40 to be mounted on the shank in four different angular positions.
Although not shown in FIGS. 1-3, it is typical for a locking cylinder to be received in the handle 12 and extend into the stepped shaft 20, so that turning of a key will extend a locking member outwardly of the stepped shaft 20 to mate with a corresponding locking groove formed within the interior of housing 10.
The installation and use of a latch as described above presents a number of disadvantages.
The transverse positioning of the actuating member 40 with respect to the handle 12 is established by tightening the positioning nut 50 against the outside face of the actuating member 40. If the nut 50 becomes loose during use, the proper adjustment may be lost. In addition, the initial installation can be made more difficult by the ability of the actuating member 40 to slide freely transversely of the shank until such time as the nut 50 is tightened.
In another aspect, the exposed return spring 70 is subject to accidental damage or dislodging during use. As described above, it must be manipulated during installation. Furthermore, because it is a separate element, the return spring 70 is subject to loss even before installation, as during transportation, sale, and the like.